Narrative:Arriving near Denver, visibility and ceiling were below company minimums, so the aircraft was cleared for the revised alternate Rock Springs, with permission to land at Laramie. Near Laramie, the crew decided to continue on to Cheyenne which then had 3500 feet ceiling and lower broken clouds, visibility 20 miles. By the time the aircraft was over the Cheyenne range, the ceiling was 900 feet with sleet. The aircraft was cleared to descend from FL140 to FL080. Severe turbulence as then encountered, including severe icing. The Curtiss C-46 lost control on approach and crashed just 2,5 miles short of the airport.

PROBABLE CAUSE: "Loss of control of the aircraft during an instrument approach to Cheyenne, under conditions of heavy icing and severe turbulence."